Science as philosophy

Science as a process includes the various means of experimentation, observation, and analysis leading to empirically testable claims about the physical universe;

Philosophy is the process by which humans develop and organize their thought processes, values, and criteria for "truth," which are not empirically testable;

Science as a process as described above cannot itself be empirically tested; on the contrary, it is a human means of understanding the universe which rests on philosophical assumptions and values, and which cannot be tested against anything except its philosophical coherence;

Therefore, science as a process is not itself scientific; rather, it is philosophical.

Assumptions of science

Philosophy of science depends on several philosophical beliefs:

Objectivity of reality: The idea that reality is objective, independent of the observer, and can be observed objectively;

Induction: The idea that an observation can be believed to be valid in all cases if it is true in all observed cases;

Coherentism: The idea that an idea can be believed to be valid if it is consistent with all other ideas held;

Parsimony: The idea that the best idea is the idea which requires the fewest assumptions to explain the observations at issue;

Theory-dependence: The idea that all observations depend on theoretical assumptions to frame and understand the observation;

Materialism and science

Some argue that materialism—or the belief that nothing can be proven to exist except matter—is an essential assumption of science. However, this assumption is false for two reasons:

Materialism has been scientifically disproven; matter has been proven to be merely one configuration of energy among many, and many other configurations of energy have no corresponding material reality;

The belief in the existence of matter and the existence of X does not preclude one from studying matter. In other words, one's ability to observe and study the material world does not require one to deny the existence of any other, non-material reality;

What is science?

Schools of thought

Positivism, a position popular in the early 20th century and still popular in some circles today, is the idea that only facts which can be empirically observed are scientific, or for that matter, meaningful.

Falsificationism, the position popularized by Karl Popper, is the idea that science includes only those ideas which can be experimentally tested. If an idea cannot be tested, it is not science, but "metaphysical," according to Popper;

Post-positivism, the position popularized by Thomas Kuhn, is the idea that the scientific community is influenced by paradigms, social, political, and ideological factors, such that science changes through paradigm shifts, in which scientists work within a paradigm until mounting problems with the current paradigm reach a breaking point and scientists switch to a new paradigm;

Feyerabandism, the position popularized by Paul Feyeraband, is the idea that science is not privileged in terms of logic or method, such that scientists carry no special authority;

Thagardism, the position popularized by Paul Thagard, is the idea that science includes those ideas taken seriously by the scientific community;

Science as objective or subjective

The schools of thought identified above can be grouped into two broad categories: those which demarcate science in objective terms (positivism and falsificationism), and those which demarcate science in subjective terms (the remaining schools of thought). The objective schools of thought conceptualize science as something which can be objectively identified based on independent criteria—essentially, an idea is scientific or unscientific regardless of what anybody thinks of the matter. The subjective schools of thought conceptualize science as what scientists think or what scientists do—thus an idea is "scientific" if it is accepted by the "scientific community," and ceases to be scientific if it is rejected by the same community.

This issue becomes important in the evolutionism vs. creationism and plate tectonics vs. expanding earth controversies. Typically, evolutionists use arguments which assume a subjective definition of science—creationism is unscientific because it is rejected by most scientists, or because it (supposedly) does not have peer-reviewed journals, or because it is "advanced for religious purposes." Creationists, on the other hand, typically use arguments that assume an objective definition of science—for example, common descent is not science, because it cannot be experimentally tested.